Food and drinks are commonly carried on long trips in cars and to vacation places or simply on picnics. Comestibles usually need to be maintained at reduced temperatures for the sake of preservation and taste.
Ice-chilled or other types of portable refrigerated food carrying systems widely used these days include varieties of thermally-insulated cold storage, or “ice” chests of a sort that are available in a variety of sizes, styles, and complexity. Some are so large as to require wheels to enhance their “portability.” These food carrying systems are commonly used with water ice or, less commonly, with “dry” ice, (i.e., solid carbon dioxide), and occasionally with mechanical, absorption, or thermoelectric refrigeration capacity built in. The electrically powered refrigerated systems that are now available are primarily of the thermoelectric type which, though initially offered as panaceas, are far from generally capable, almost pitifully incapable of achieving the desired cooling effectiveness, and they can be unreliable. Thermoelectric systems also require electrical power connections which add to the overall weight, complexity and use requirements. In general, the refrigeration capacity of thermoelectric systems, especially when warm foods or drinks are placed within the refrigeration system, is poor.
The typical portable non-electric food-carrying and storage systems consist of an insulated box that often includes a movable shelf that is sometimes used to hold ice or frozen packages of salt solutions intended to impart refrigeration to, or absorb heat from, the materials being chilled. Some people use frozen milk cartons full of water as storage for refrigeration, while many people use simple plastic bags of ice to provide refrigeration. However, distribution of the refrigeration is often uneven. There is also the problem of meltwater, which can accumulate a the bottom of a food container, thereby rendering baked goods and other foods soggy and unpleasant.